Process for manufacturing bristles for a vehicle washing brush, bristles obtained by this process and brushes made with said bristles

ABSTRACT

Bristles for brushes for washing vehicles are made by molding closed-cell polyolefin foam in a pressurized mold to form a block. The block then is cut into sheets to form the brush bristles.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for manufacturing bristles for brushes for washing motor vehicles, particularly automotive vehicles including buses and trucks, but also subway or overground trains. The invention also deals with the bristles obtained by this method and with the brushes produced from such bristles.

2. Description of the Related Art

Automatic vehicle-washing installations are currently for the most part equipped with brushes made of extruded polyethylene filament of cruciform cross section, the diameter of which varies between 0.6 and 1.2 mm. Such brushes are relatively heavy when wet, because a fine film of water becomes deposited over the entire surface area of the bristles. As a result, under the effect of the kinetic energy of the bristles, a very light coating of material is deposited on the vehicles during washing, giving a dull appearance to dark colors in particular.

Also known are washing brushes of the “foam” type, in which the bristles are made of a closed-cell extruded plastic foam. Such bristles are considered to be gentler on the bodywork, particularly since they are lighter in weight. However, when the surface skin obtained at the time of extrusion is worn or damaged, the closed cells on the periphery find themselves open and then fill with water. Now, the extrusion method allows only relatively large cells to be obtained. It then follows that the bristles become considerably heavier and then exhibit the same disadvantages as the conventional extruded polyethylene filaments.

SUMMARY OF THE INVENTION

It is therefore the main object of the present invention to remedy these disadvantages and, to this end, the subject of the invention is a method for manufacturing brush bristles made of plastic foam for washing vehicles which is essentially characterized in that it consists in producing closed-cell polyolefin foam in a pressurized mold in the form of a block which is then cut into sheets, then into strips, so as to form brush bristles.

The pressurized molding method makes it possible to obtain closed cells which are far smaller than can be obtained with the extrusion method. It then follows that even when wet, the brush bristles thus obtained remain relatively light in weight and do not therefore damage vehicle bodywork. In addition, as the cells are smaller, they do not hold on to the particles of dirt and it is therefore not necessary to anticipate a high-pressure water prewash.

In one particular embodiment of the invention, the molding pressure is above 5000 kPa, and this makes it possible to obtain even smaller cells.

As a preference, the polyolefin foam is chemically cross-linked, and this makes it possible in particular to improve the mechanical strength and chemical resistance of the product.

As a preference also, the polyolefin foam has a density of between 150 and 200 kg/m³, with represents a good compromise between products lightness and strength.

As a further preference, the polyolefin foam has a density of 170 kg/m³.

According to another feature of the present invention, the brush bristles thus obtained have a cross section ranging from 0.2 cm to 1.5 cm.

As a preference, the bristles have a rectangular cross section measuring 0.3 cm by 0.6 cm, so as to have maximum effectiveness.

According to yet another feature of the invention, the vehicle washing brushes produced from the bristles thus obtained consist of standard cavity sheets in which the bristles are fixed in the traditional way.

As an alternative, each cavity sheet comprises both foam bristles according to the invention and conventional extruded plastic bristles.

According to another alternative, the brush comprises bristles of two different lengths.

According to yet another alternative, the long bristles consist of foam bristles according to the invention, while the short bristles consist of conventional extruded plastic bristles.

BRIEF DESCRIPTION OF THE DRAWINGS

One embodiment of the invention is described hereinbelow by way of example, with reference to the attached drawing in which:

FIG. 1 is a side view of a portion of a cavitied support plate in which polyolefin foam bristles according to the invention are mounted and which is intended for producing vehicle washing brushes.

FIG. 2 is a view of the reverse side of this portion of support sheet.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1 and 2 show a portion of a support plate 1 provided with a multitude of cavities 2. This support sheet 1, made of flexible plastic, is intended to be mounted on a brush shaft that forms part of an automatic vehicle-washing installation, not depicted.

Fixed into each cavity 2 is a tuft of bristles 3 which tuft is held in place in the traditional way using a nylon filament 4.

According to the invention, the brush bristles 3 are obtained according to a method that consists in producing closed-cell polyolefin foam in a pressurized mold, in the form of a block which is then cut into sheets, then into strips, strands or filaments, in order thus to form brush bristles than can be mounted in the cavities 2 of the sheets 1.

The molding pressure is normally above 5000 kPa and the polyolefin foam is chemically cross-linked within the mold, the cross-linking and foaming taking place simultaneously during one heating phase.

The density of the product will advantageously be between 150 and 200 kg/m³ and will preferably be equal to 170 kg/m³.

By way of information, it would for example be possible to choose material by the trade name of ALVEOLUX marketed by the Japanese company SEKISUI.

The strands of foam that make up the bristles of the brush may have a cross section ranging from 0.2 cm to 1.5 cm. Tests have shown that a rectangular cross section measuring 0.3 cm by 0.6 cm gave excellent results.

The washing brushes thus produced have numerous advantages over the brushes hitherto employed.

The material used first of all has excellent physical properties, particularly suppleness and strength which make it particularly well suited to the work of brushing vehicles in an aqueous environment laden with various products. The inertness with respect to most chemical products is very important and allows the use of all the products currently employed in washing systems: soaps, detergents, polishes, drying products, etc.

Furthermore, the low water absorption of the chemically cross-linked polyolefin foam, which is due in particular to the fact that its closed cells are particularly small, allows the brush as a whole not to become heavier over the course of successive washing operations. In addition, the size of these cells is such that the cells are unable to hold on to the abrasive particles removed during washing and which could damage vehicle bodywork. There is therefore no need to anticipate high pressure prewashing, and this represents a not insignificant cost saving and a considerable time saving.

In an alternative form of embodiment of the invention, it may be anticipated for the support sheet 1 to comprise both bristles 3 according to the invention and extruded plastic conventional bristles.

It may also be anticipated for the washing brush to comprise bristles of two different lengths, as described in French patent No. 97 05513 dated May 5, 1997. In this case, the long bristles will be made of foam according to the invention, while the short bristles will be made of conventional extruded plastic bristles. 

1. A method for manufacturing brush bristles made of plastic foam for washing vehicles, which method consists in producing closed-cell polyolefin foam in a pressurized mold in the form of a block which is then cut into sheets, then into strips, so as to form brush bristles.
 2. The method as claimed in claim 1, wherein the molding pressure is higher than 5000 kPa.
 3. The method as claimed in claim 1, wherein the polyolefin foam is chemically cross-linked.
 4. The method as claimed in any one of claims 1, wherein the polyolefin foam has a density of between 150 and 200 kg/m³.
 5. The method as claimed in claim 4, wherein the polyolefin foam has a density of 170 kg m³.
 6. Brush bristles obtained by the method as claimed in claim 1, which bristles have a cross section ranging from 0.2 cm to 1.5 cm.
 7. The bristles as claimed in claim 6, and which have a rectangular cross section measuring 0.3 cm by 0.6 cm.
 8. A vehicle washing brush produced from brush bristles obtained by the method of claim 1, and which consists of standard cavity sheet in which the bristles are fixed in the traditional way.
 9. The brush as claimed in claim 8, wherein the brush further includes conventional extruded plastic bristles.
 10. The brush as claimed in claim 9, which brush comprises bristles of two different lengths.
 11. The brush as claimed in claim 10, wherein the long bristles consist of the foam bristles, while the short bristles consist of the conventional extruded plastic bristles. 